This invention relates to filter assemblies and, more particularly, to filter assemblies for removing relatively fine, suspended solid particles from a fluid such as a waste water.
Vehicle washing facilities typically include a system for reclaiming "dirty" wash water. These reclaim systems usually include a sump, pit or holding tank in which the "dirty" wash water is collected and heavy particles, such as sand, gravel, etc. settle out. Before reuse the partially clarified water is passed through some type of filtration apparatus, such as sand filters, centrifugal separators, etc., to remove fine suspended solid particles, such as leaves, cigarette paper, etc. which can clog the spray nozzles and other components in the washing equipment.
Sand filters include relatively complicated piping and valving for the periodic back flushings required for cleaning. Centrifugal separators do not effectively remove smaller, lighter weight particles. Both sand filters and centrifugal separators require one or more pumps larger than that required to draw water from the sump in order to create the head required to force the water through the sand bed(s) or generate the required centrifugal action. Consequently, in addition to a substantial initial investment, operating and maintenance costs can be quite high for such filtration apparatus.
Filtration assemblies including longitudinally collapsible flexible filter units have been used for different applications. Examples of such filtration assemblies are disclosed in U.S. Pat. Nos. 1,145,372 (Krause), 3,997,446 (Nagakura) and 4,062,773 (Leonard). However, such assemblies generally are much too complicated for reliable use in a wash water reclaim system and/or not arranged to be self-cleaning.